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Flue Gas Desulfurization by Calcined Phosphate Rock and Reaction Kinetics

Naktiyok, Jale, Bayrakçeken, Hatice, Özer, A. Kadir, Gülaboğlu, M. Şahin
Energy & Fuels 2013 v.27 no.3 pp. 1466-1472
activation energy, air, carbon dioxide, chemical reactions, flue gas desulfurization, fluidized beds, mercury, models, porosity, reaction kinetics, rock phosphate, sulfur dioxide, surface area, temperature
The phosphate rock was calcined at temperatures ranging between 775 and 850 °C in a fluidized bed using air. The changes in the pore structure and surface area of the calcined phosphate samples were determined by a mercury porosimeter and Brunauer–Emmett–Teller (BET) analysis. It was determined that the calcined phosphate samples at 850 °C for 8 min have the highest surface area, particle volume, and porosity. Then, the reaction kinetics of SO₂ with calcined phosphate sample (at 850 °C for 8 min) was investigated in a differential fluidized bed by changing the sulfation temperature and SO₂ and CO₂ concentrations. It was observed that the sulfation ratio increased with an increasing temperature and SO₂ concentration but decreased with an increasing CO₂ concentration. The sulfation reaction was well-represented by a shrinking core model, which can be divided into two regions with different rate controlling steps. For low conversions, the controlling step was found to be the chemical reaction at the interface but the diffusion through the product layer for high conversion. The activation energies for the chemical reaction at the interface and the diffusion through the product layer were calculated as 92 and 197 kJ mol–¹, respectively.